HESIONIDAE (ANNELIDA, POLICHAETA) FROM JAPAN. I. by Hiro ...

38 Kuroshio Biosphere : BULL. BIOL. INST. KUROSHIO Vol. 1, 2004
constrictions is related to the position of acicular papillae, where the tips of acicula
penetrated.
Presetal lobe in neuropodia seems to be specifically quite stable in form. Very
inconspicuous (O. minutus (Hartmann-Schröder, 1959), for example), narrow triangular
(O. berrisfordi Day, 1967, and C. constrictus, n. sp. for example), cylindrical with a round
tip (O. bunbuku, n. sp., for example), wide triangular with dull tip (O. pugettensis
(Johnson, 1901) for example), wide triangular with pointed tip (O. agilis (Ehlers, 1864)
and O. parapallidus, n. sp. for example), and long triangular (O. fauveri, n. sp. and O.
okudai, n. sp. for example) are present.
Postsetal lobe in neuropodia is also specifically stable in form. Long triangular (O.
fauveri, n. sp. and O. parapallidus, n. sp., for example), rounded (O. agilis (Ehlers, 1864),
O. pugettensis (Johnson, 1901), and O. brevipodius, n. sp., for example), and almost
truncated (O. berrisfordi Day, 1967, O. bunbuku, n. sp., and O. constrictus, n. sp., for
example) are present.
The position of insertion of neurocirri is also specific. Neurocirri are inserted at
ventro-lateral corner of parapodia in some species such as O. brevipodius, n. sp., but those
are inserted more inside of ventral edge of parapodia in other species such as O. bunbuku,
n. sp.
Presence of long blade neurosetae is also specific. During the survey of several
species of Ophiodromus, it is found that some species with sub-acicular long blade
neurosetae together with short blade setae, but other species without such sub-acicular
setae, and furthermore, found that the species with long blade sub-acicular neurosetae, also
have very long blade neurosetae in their supla-acicular position.
Some species with pale colored bands on the dorsum of some segments. The bands
are brightly white with blue-green tint in living condition. Degree of development of the
white bands shows variety by individuals, but the positioning of the bands in anterior part
of the body (until Segment XXXV (?), cf. Okuda, 1936, p. 414) very stable in the same
species, and the presence of the white bands is also specifically stable.
Parasyllidia Pettibone, 1961 is very similar to Ophiodromus. The difference is only
presence or absence of median antenna. Parasyllidia humesi, the type species, was
described based on the type series of over 200 individuals of specimens collected from the
mantle cavity of a species of bivalve molluscs. The median antenna of Ophiodromus
species is occasionally missing while collection or treatment of fixed condition. However, it
is difficult to consider that all the type specimens of over 200 individuals lost their median
antennae before Pettibone's check. Whatever P. humesi is devoid of a median antenna, the
species is too much similar to O. berrisfordi Day, 1967.
The other species hitherto referred to Parasyllidia [P. blacki (Knox, 1960)] may be
the specimens of the genus Ophiodromus of their median antennae thrown off (see p. 43).
Nereimyra longicirrata Knox & Cameron, 1971 may be the members of the genus
Ophiodromus. Gyptis vittata Webster & Benedict, 1887 is also in the same condition. (cf.
the key to the species of the genus Ophiodromus, p. 65)
On the other hand, Podarke comata Ehlers, 1913 may be a species of the genus
Gyptis. The description shows the species with papillae on its proboscis. Ophiodromus
tigrinus Rullier, 1972 may also belong to another genus. The species has not 6 pairs of